GAITHERSBURG, Md. and SEATTLE - April 23, 2015 — MedImmune, the global biologics research and development arm of AstraZeneca, and Juno Therapeutics, Inc., a biopharmaceutical company focused on re-engaging the body's immune system to revolutionize the treatment of cancer, announced today that they have entered into a new collaboration to conduct combination clinical trials in immuno-oncology with one of Juno’s investigational CD19-directed chimeric antigen receptor (CAR) T cell candidates and MedImmune’s investigational programmed cell death ligand 1 (PD-L1) immune checkpoint inhibitor, MEDI4736. Under the initial development plan, both companies will explore the safety, tolerability and preliminary efficacy of the combination therapy as a potential treatment for patients with non-Hodgkin lymphoma (NHL).

“We are pleased to enter into this clinical trial collaboration with Juno Therapeutics as our initial venture into the promising emerging field of CAR T cell therapies,” said Dr. Ed Bradley, Senior Vice President and Head of the Oncology Innovative Medicines unit, MedImmune. “The combination of Juno’s CAR T cell candidate with MEDI4736 adds to our broad program of immuno-oncology combination trials, addressing multiple immune pathways and working with industry-leading partners to explore the significant potential of immunotherapies in transforming treatments for cancer.”

Under the terms of the non-exclusive collaboration, MedImmune and Juno will jointly co-fund the initial Phase Ib study, which is expected to begin later in 2015. The companies will also explore the combination of MEDI4736 with a next-generation, Juno-developed fully human CD19-directed CAR T cell candidate.

“We believe combination strategies such as this will help us better understand the full potential of our engineered T cell platform in both hematological and solid tumor settings,” said Mark W. Frohlich, M.D., Executive Vice President, Research & Development at Juno Therapeutics. “We look forward to working with MedImmune, a leader in immuno-oncology and checkpoint inhibition, in understanding the potential clinical benefit of combining these two potent therapeutic classes.”

Financial details were not disclosed.

About MEDI4736MEDI4736 is an investigational human monoclonal antibody directed against programmed cell death ligand 1 (PD-L1). Signals from PD-L1 help tumors avoid detection by the immune system. MEDI4736 blocks these signals, countering the tumor’s immune-evading tactics.

MEDI4736 was accelerated into Phase III clinical development in non-small cell lung cancer and head and neck cancer. The OCEANS clinical development program will evaluate MEDI4736 as monotherapy and in combination with a CTLA-4 (tremelimumab) in lung cancer, across the spectrum of the disease. In head and neck cancer, MEDI4736 is being investigated both as monotherapy and in combination with tremelimumab, looking at patients with different PD-L1 expression status who have failed on chemotherapy.

About Chimeric Antigen Receptor (CAR) TechnologyJuno’s chimeric antigen receptor (CAR) technology genetically engineers T cells to recognize and kill cancer cells. Juno’s CAR T cell technology inserts a gene for a particular CAR into the T cell, enabling it to recognize cancer cells based on the expression of a specific protein located on the cell surface. When the engineered T cell engages the target protein on the cancer cell, it initiates a cell-killing response against the cancer cell.

About AstraZenecaAstraZeneca is a global, innovation-driven biopharmaceutical business that focuses on the discovery, development and commercialisation of prescription medicines, primarily for the treatment of cardiovascular, metabolic, respiratory, inflammation, autoimmune, oncology, infection and neuroscience diseases. AstraZeneca operates in over 100 countries and its innovative medicines are used by millions of patients worldwide. For more information please visit: www.astrazeneca.com.

About MedImmuneMedImmune is the worldwide biologics research and development arm of AstraZeneca, a global, innovation-driven biopharmaceutical business that focuses on the discovery, development and commercialization of small molecule and biologic prescription medicines. MedImmune is pioneering innovative research and exploring novel pathways across key therapeutic areas, including respiratory, inflammation and autoimmunity; cardiovascular and metabolic disease; oncology; neuroscience; and infection and vaccines. The MedImmune headquarters is located in Gaithersburg, Md., one of AstraZeneca's three global R&D centres. For more information, please visit www.medimmune.com.

About JunoJuno Therapeutics, Inc. is building a fully integrated biopharmaceutical company focused on revolutionizing medicine by re-engaging the body's immune system to treat cancer. Founded on the vision that the use of human cells as therapeutic entities will drive one of the next important phases in medicine, Juno is developing cell-based cancer immunotherapies based on chimeric antigen receptor and high-affinity T cell receptor technologies to genetically engineer Tcells to recognize and kill cancer. Juno is developing multiple cell-based product candidates to treat a variety of B-cell malignancies as well as solid tumors. Several product candidates have shown compelling evidence of tumor shrinkage in the clinical trials in refractory leukemia and lymphoma conducted to date. Juno's long-term aim is to improve and leverage its cell-based platform to develop new product candidates that address a broader range of cancers and human diseases. Juno brings together innovative technologies from some of the world's leading research institutions, including the Fred Hutchinson Cancer Research Center, Memorial Sloan Kettering Cancer Center, Seattle Children's Research Institute, and The National Cancer Institute.

Juno Forward Looking StatementsThis press release contains forward-looking statements, including statements regarding the funding, timing, conduct, and benefits of collaboration between the companies. Forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from such forward-looking statements, and reported results should not be considered as an indication of future performance. These risks and uncertainties include, but are not limited to, risks associated with: the success, cost, and timing of Juno’s product development activities and clinical trials, and Juno’s ability to finance these activities and trials; Juno’s ability to obtain regulatory approval for and to commercialize its product candidates; Juno’s ability to establish a commercially-viable manufacturing process and manufacturing infrastructure; regulatory requirements and regulatory developments; success of Juno’s competitors with respect to competing treatments and technologies; Juno’s dependence on third-party research institution collaborators and other contractors in Juno’s research and development activities, including for the conduct of clinical trials and the manufacture of Juno’s product candidates; Juno’s ability to obtain, maintain, or protect intellectual property rights related to its product candidates; amongst others. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Juno's business in general, see Juno's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 19, 2015 and Juno’s other periodic reports filed with the Securities and Exchange Commission. These forward-looking statements speak only as of the date hereof. Juno disclaims any obligation to update these forward-looking statements.

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